Systems and methods of transmitter protection for wireless communications

ABSTRACT

Various embodiments provide for systems and methods for wireless communications that implement transmitter protection schemes using spatial combining. The protection scheme implemented by some embodiments provides for a number of benefits, including without limitation: hitless protection; constant power monitoring for each wireless channel being utilized; extra gain to wireless signals transmitted; beam steering, beam hopping, and beam alignment capabilities; and varying levels of transmission path protection (e.g., 1+1 protection, or 1+N protection). Additionally, the features of some embodiments may be applied to a variety of wireless communications systems including, for example, microwave wireless systems, cellular phone systems and WiFi systems.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Nonprovisional applicationSer. No. 14/016,992, filed Sep. 3, 2013, entitled, “Systems and Methodsof Transmitter Protection for Wireless Communications,” which is acontinuation of Ser. No. 13/249,186 filed Sep. 29, 2011, entitled“Systems and Methods of Transmitter Protection for WirelessCommunications,” and now U.S. Pat. No. 8,526,895, which claims priorityto U.S. Provisional Application Ser. No. 61/387,932 filed Sep. 29, 2010,entitled “Smart Transmitter Protection Schemes for Radio Optimized forSingle RFU.” All of the applications referenced in this paragraph arehereby incorporated by reference herein.

FIELD OF THE INVENTION(S)

The present invention(s) relate to wireless communications systems, andmore particularly, some embodiments relate to systems and methods forwireless communications utilizing a transmitter protection scheme.

DESCRIPTION OF THE RELATED ART

In wireless communications systems, protection schemes are an essentialcomponent to ensuring overall availability and reliability ofcommunications services. This is particularly true for radio backhaulnetworks (e.g., microwave or millimeter wave radio systems) whichprovide the necessary infrastructure for many of today's wirelesscommunications networks. Unfortunately, due to network costs andtechnology limitations, there has been little to no recent developmentin the area of protection schemes for wireless communications.Naturally, many modern wireless communications systems are left toimplement traditional protection schemes in order to achieveavailability and reliability goals.

One such traditional protection scheme is 1+1 which provides radio linkredundancy between two communications sites using two (often identical)transmitting radio frequency units. Under 1+1 protection, onetransmitting radio frequency unit is in active mode (i.e., the maintransmitting radio frequency unit) while the other is in stand-by mode(i.e., the secondary transmitting radio frequency unit) and remainsmuted. If the main transmitting radio frequency unit fails, thesecondary transmitting radio frequency unit may switch to active modeand assume the role of the primary transmitter. Generally, performancesuffers a time delay associated with switching from the maintransmitting radio frequency unit to the secondary transmitting radiofrequency unit.

FIG. 1 depicts a main active transmitting radio frequency unit (RFU) 102and a secondary inactive backup transmitting RFU 104 with separateantennas 110 and 114 in the prior art. In an environment 100, a mainactive transmitting RFU 102 transmits data through the antenna 110 viathe diplexer 108 to the wireless communication receiver 106. Thesecondary inactive backup transmitting RFU 104 may be muted or otherwiseinactive. It is not uncommon that the secondary inactive backuptransmitting RFU 104 is powered and ready to be made active therebyacting as a backup to the main active transmitting RFU 102.

If the main active transmitting RFU 102 fails or falls below anacceptable level of performance, the main active transmitting RFU 102may be muted or may be inactivated. Subsequently, the secondary inactivebackup transmitting RFU 204 may be activated. As a result, the formerlysecondary inactive backup transmitting RFU 204 will become the primarytransmitting unit and provide the signal to the antenna 114 via thediplexer 112 for transmission to the wireless communication receiver106.

Another traditional protection scheme is 1+N protection Like 1+1protection, 1+N protection utilizes one transmitting RFU as the maintransmitting RFU. 1+N protection differs from 1+1 protection in that,instead of having only one secondary backup transmitting RFU as a backupunit in stand-by mode, there are N number of secondary backuptransmitting RFUs. Accordingly, 1+N protection provides additionallevels of redundancy over 1+1 protection. Unfortunately, the time delayassociated with switching from an active mode RFU to one of the stand-bymode RFUs still exists under 1+N protection.

SUMMARY OF EMBODIMENTS

Various embodiments provide for systems and methods for wirelesscommunications that implement spatial combining. In some embodiments, awireless communications system may comprise first and secondtransmitting radio frequency units. The first and second transmittingradio frequency units may be a part of a microwave communication system.In one example, the first and second transmitting radio frequency unitsare a part of a peer-to-peer microwave communication system.

The first transmitting radio frequency unit may have a first radiofrequency path with the receiving radio frequency unit. The secondtransmitting radio frequency unit may also have a second radio frequencypath with the receiving radio frequency unit. In some embodiments, thefirst transmitting radio frequency unit is configured to transmit afirst wireless signal, having a first phase and a first amplitude, tothe receiving radio frequency unit over the first radio frequency path.The second transmitting radio frequency unit may also be configured totransmit a second wireless signal, having a second phase and a secondamplitude, to the receiving radio frequency unit over the second radiofrequency path. The first transmitting radio frequency unit and thesecond transmitting radio frequency unit may be further configured tosynchronize the first phase and the second phase, synchronize the firstamplitude and the second amplitude, and transmit the first wirelesssignal and second wireless signal such that the first wireless signaland the second wireless signal spatially combine to form a beam, to thereceiving radio frequency unit, that comprises the input signal. In someembodiments, synchronizing the first and second phase and/or gaincomprises each transmitting radio frequency unit adjusting the phase andgain (i.e., amplitude) of a signal based on a comparison to apredetermined phase and gain.

In some embodiments, the first transmitting radio frequency unit and thesecond transmitting radio frequency unit implement a 1+1 protectionscheme. In some embodiments, each transmitting radio frequency unit maycontinue to transmit a signal to a receiving radio frequency unit, or aplurality of receiving radio frequency units, even when one of the twotransmitting radio frequency units has ceased transmission (e.g., due toequipment failure) or fallen below an acceptable standard ofperformance.

In various embodiments, where either the first or second transmittingradio frequency unit comprises a plurality of transmitting radiofrequency units, the first transmitting radio frequency unit and thesecond radio frequency unit may implement a 1+N protection scheme. Insome embodiments, one or more transmitting radio frequency units maycontinue to transmit the wireless signal to a receiving radio frequencyunit, or a plurality of receiving radio frequency units, even when oneor more of the transmitting radio frequency units has ceasedtransmission (e.g., due to equipment failure) or fallen below anacceptable standard of performance.

Spatially combining the first wireless signal and the second wirelesssignal to form the beam may involve adjusting the first phase and thesecond phase, or adjusting the first amplitude and the second amplitude.In some embodiments, adjusting the phase or the amplitude in atransmitting radio frequency unit may comprise adjusting an in-phasecomponent of a baseband signal or adjusting a quadrature component ofthe same baseband signal.

In some embodiments, the first transmitting radio frequency unit and thesecond transmitting radio frequency unit may belong to an analogbeamforming network where, for example, each of the first transmittingradio frequency unit and the second frequency unit may comprise a phaseshifter module configured to adjust a phase, and an AGC moduleconfigured to adjust an amplitude. In various embodiments, the firsttransmitting radio frequency unit and the second transmitting radiofrequency unit may belong to a digital beamforming network. In someembodiments, each of the first and second transmitting radio frequencyunits may adjust the in-phase component of a baseband signal used in thegeneration of a wireless signal, or adjust the quadrature component ofthe same baseband signal.

According to various embodiments, an exemplary method may comprisereceiving an input signal to be transmitted, generating a plurality ofindividual wireless signals from the input signal, wherein eachindividual wireless signal of the plurality of individual wirelesssignals has a phase and a amplitude, adjusting the phase of eachindividual wireless signal of the plurality of individual wirelesssignals such that the phase matches, or meets a condition based on, apredetermined phase value, wherein the predetermined phase enables theplurality of individual wireless signals to spatially combine to form abeam, adjusting the amplitude of each individual wireless signal of theplurality of individual wireless signals such that the amplitudematches, or meets a condition based on, that a predetermined gain valueof all other individual wireless signals of the plurality of individualwireless signals, wherein the predetermined gain value enables theplurality of individual wireless signals to spatially combine to formthe beam comprising the input signal to be transmitted, and transmittingeach individual wireless signal of the plurality of individual wirelesssignals over a wireless channel to the receiving radio frequency unitsuch that the plurality of individual wireless signals spatially combineto form a beam, over the wireless channel, that comprises the inputsignal to be transmitted.

The method may further comprise determining the predetermined phasevalue and the predetermined gain value (i.e., predetermined gain value)for the plurality of individual wireless signals such that thepredetermined phase and the predetermined gain enable the plurality ofindividual wireless signals to spatially combine to form the beamcomprising the input signal. Depending on the embodiment, thisdetermination may happen before the phase or the amplitude of eachindividual wireless signal of the plurality of individual wirelesssignals is adjusted.

In some embodiments, the method may further comprise determining a newpredetermined phase value or a new predetermined gain value for theplurality of individual wireless signals when an individual wirelesssignal is added to or removed from the plurality of individual wirelesssignals, wherein the new predetermined phase value or the newpredetermined gain value enables the plurality of individual wirelesssignals to spatially combine to form the beam comprising the inputsignal. For example, where each of the plurality of individual wirelesssignals is being transmitted by a separate transmitting radio frequencyunits, and one or more of those separate transmitting radio frequencyunits eventually stops transmitting (e.g., due to a component failure)or falls below an acceptable level of performance, there may be fewerindividual wireless signals being transmitted. To compensate for thisaddition or removal of an individual wireless signal from the pluralityof individual wireless signals, a method in accordance with someembodiments may determine a new predetermined phase value or a newpredetermined gain value for the plurality of individual wirelesssignals such that the plurality of individual wireless signals can stillform a beam carrying the input signal to be transmitted.

Depending on the embodiment, each individual wireless signal of theplurality of individual wireless signals may be transmitted over thewireless channel simultaneously, or in some alternative sequence.

Additionally, in some embodiments, when an individual wireless signal isadded to or removed from the plurality of individual wireless signals,the method may further comprise readjusting the phase or the amplitudeof each remaining wireless signal of the plurality of individualwireless signals still being transmitted. Depending on the embodiment,the phase and amplitude may be readjusted to respectively match, or meeta condition based on, a new predetermined phase or a new predeterminedgain, where the new predetermined phase and the new predetermined gainenable a beam carrying the input signal to be formed.

According to some embodiments, an exemplary system comprises a means fortransmitting a first wireless signal the receiving radio frequency unit,the first wireless signal having a first phase and a first amplitude; ameans for transmitting a second wireless signal the receiving radiofrequency unit, the second wireless signal having a second phase and asecond amplitude, a means for synchronizing the first phase with thesecond phase, a means for synchronizing the first amplitude with thesecond amplitude, and a means for spatially combining the first wirelesssignal and the second wireless signal to form a beam, to the receivingfrequency unit, that comprises the input signal. In some embodiments,the means for transmitting the first wireless signal and the means fortransmitting the second wireless signal may implement a 1+1 protectionscheme with the receiving radio frequency unit.

In some embodiments, the system may further comprise a means foradjusting the first phase, and a means for adjusting the second phase,where the means for adjusting the first phase and the means foradjusting the second phase are used to spatially combine the firstwireless signal and the second wireless signal to form the beam.Additionally, in some embodiments, the system may further comprise ameans for adjusting the first amplitude, and a means for adjusting thesecond amplitude. Depending on some embodiments, the means for adjustingthe first amplitude and the means for adjusting the second amplitude maybe used to spatially combine the first wireless signal and the secondwireless signal to form the beam.

In some embodiments, the wireless communications system may furthercomprise a means for transmitting N−1 wireless signals to the receivingradio frequency unit, the N−1 wireless signals having a third phase anda third amplitude, a means for synchronizing the third phase with thefirst phase and the second phase, a means for synchronizing the thirdamplitude with the first amplitude and the second amplitude, and a meansfor spatially combining the N−1 wireless signals with the first wirelesssignal and the second wireless signal to form the beam. In some suchembodiments, the means for transmitting the first wireless signal, themeans for transmitting the second wireless signal, and the means fortransmitting the N−1 wireless signals may be used to implement a 1+Nprotection scheme with the receiving radio frequency unit.

According to some embodiments, various steps described herein may beimplemented using a digital device. For instance, some embodimentsprovide for a computer program product comprising a computer readablemedium (e.g., a hard drive, optical medium, floppy disk, thumbdrive, orthe like) having computer program code embodied therein for causing acomputing device (i.e., a digital device) to perform specific stepsdescribed herein.

Other features and aspects of various embodiments will become apparentfrom the following detailed description, taken in conjunction with theaccompanying drawings, which illustrate, by way of example, the featuresof the various embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a main active transmitting radio frequency unit (RFU) anda secondary inactive backup transmitting RFU with separate antennas inthe prior art.

FIG. 2 is a diagram illustrating an exemplary system including atransmitting radio frequency unit in accordance with some embodiments.

FIG. 3 is a block diagram of a signal quality module for controllingboth phase and gain of the signal in some embodiments.

FIG. 4 depicts two transmitting radio frequency units in someembodiments

FIG. 5 depicts another transmitting radio frequency unit in someembodiments.

FIG. 6 depicts two transmitting radio frequency units in someembodiments.

FIG. 7 is a flowchart of an exemplary method for transmitting a wirelesssignal in accordance with some embodiments.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

In various embodiments, systems and methods for wireless communicationsthat implement a transmitter protection scheme using spatial combiningare discussed herein. Various wireless communications systems include,for example, microwave wireless systems, cellular phone systems, andWiFi systems. The protection scheme implemented by some embodiments mayprovide any number of benefits, including but not limited to, hitlessprotection, constant power monitoring for each wireless channel, extragain, beam steering capabilities, beam hopping capabilities, beamalignment capabilities, and/or varying levels of transmission pathprotection (e.g., 1+1 protection, or 1+N protection).

FIG. 2 is a diagram illustrating an exemplary system 200 including atransmitting radio frequency unit 202 in accordance with someembodiments. The transmitting radio frequency unit 202 may compriseamplification/attenuation modules 204, 218, and 228, mixer modules 206,220, and 232, oscillator modules 210 and 224, filter modules 208, 212,222, 226, and 234, a phase adjuster 214, an AGC module 216, a signalquality module 230, a waveguide filter 244, and a waveguide 246.

The amplification/attenuation modules 204, 218, and 228 may comprise anamplifier and/or an attenuator configured to amplify and/or attenuate asignal. The amplification/attenuator modules 204, 218, and 228 may beany kind of amplifiers and/or attenuators. Further, theamplification/attenuator modules 204, 218, and 228 may each compriseamplifiers and/or attenuators with any kind of electrical properties.

In some embodiments, the amplifier/attenuator module 204 receives asignal from a modem or DSP. The amplifier/attenuator module 218 mayreceive a signal from the AGC module 216. Further, theamplifier/attenuator module 228 may attenuate the signal (or componentsof the signal) after the signal has been upconverted by the mixer module220, the filter module 222, and the oscillator module 224. Theamplifier/attenuator module 228 may then provide the signal to thesignal quality module 230 and/or the waveguide filter 244. Theamplifier/attenuator modules 204, 218, and 228 may amplify or attenuatethe signal.

Those skilled in the art will appreciate that each of theamplifier/attenuator modules 204, 218, and 228 may be the same as one ormore other amplifier/attenuator modules. For example,amplifier/attenuator modules 204, 218, and 228 may both be amplifierssharing the same electrical properties. In another example,amplifier/attenuator modules 204, 218, and 228 may both be amplifiersbut have different electrical properties.

Each amplifier/attenuator module 204, 218, and 228 may include one ormore components. For example, the amplifier/attenuator module 204 maycomprise one or more amplifiers and/or attenuators.

The mixer module 206, filter module 208, and the oscillator module 210may represent an upconverter configured to upconvert one or more signalsfrom the amplifier/attenuator module 204 to an intermediate frequency(IF) signal. Similarly, the mixer module 220, filter module 222, andoscillator module 224 also may represent an upconverter configured tofurther upconvert the IF signal to an RF signal. Those skilled in theart will appreciate that there may be any number of upconvertersconfigured to upconvert the signals within the transmitting radiofrequency unit 202.

The mixer modules 206, 220, and 232 may comprise mixers configured tomix signal(s) with one or more other signals. The mixer modules 206,220, and 232 may comprise many different types of mixers with manydifferent electrical properties. In one example, the mixer module 206mixes a signal received from the amplifier/attenuator module 204 withthe filtered oscillating signal from the filter module 208 and theoscillator module 210. In another example, the mixer module 220 mixes asignal received from the amplifier/attenuator module 218 with thefiltered oscillating signal from the filter module 222 and theoscillator module 224. The mixer module 232 may mix a signal receivedfrom the oscillator module 224 with the RF signal from theamplifier/attenuator module 228.

Those skilled in the art will appreciate that each of the mixers 206,220, and 232 may be the same as one or more other mixer modules. Forexample, mixer modules 206, 220, and 232 may both be mixers sharing thesame electrical properties or, alternately, the mixer modules 206, 220,and 232 may be another kind of mixer and/or with different electricalproperties.

Each mixer modules 206, 220, and 232 may include one or more components.For example, the mixer module 206 may comprise one or more mixers.

The filter modules 208, 212, 222, 226, and 234 may comprise filtersconfigured to filter the signal. The filter modules 208, 212, 222, 226,and 234 may comprise many different types of filters (e.g., bandpassfilter, low pass filter, high pass filter, or the like) with manydifferent electrical properties. In one example, the filter module 208may be a band pass filter configured to filter the oscillation signal(or components of the signal) provided from the oscillator module 210.Similarly, filter modules 212, 222, 226, and 234 may filter signals (orcomponents of the signals) from the mixer module 206, oscillator module224, the mixer module 220, or the mixer module 232, respectively.

Those skilled in the art will appreciate that each of the filter modules208, 212, 222, 226, and 234 may be the same as one or more other filtermodules. For example, filters module 208 and 212 may both be filterssharing the same electrical properties while filter module 222 may beanother kind of filter. In another example, filters module 208 and 212may both be filters of a similar type but have different electricalproperties.

Each filter modules 208, 212, 222, 226, and 234 may include one or morecomponents. For example, the filter modules 208 may comprise one or morefilters.

The oscillator modules 210 and 224 may comprise oscillators configuredto provide an oscillating signal that may be used to upconvert thesignal. The oscillator modules 210 and 224 may comprise any kind ofoscillator with any different electrical properties. In one example, theoscillator module 210 provides an oscillating signal to the filtermodule 208. The oscillator module 224 may provide an oscillating signalto the filter module 222.

The oscillator modules 210 and 224, either individually or together, maybe local or remote. In one example, the oscillating module 210 and/orthe oscillating module 224 may be remotely located and configured toprovide an oscillating signal to one or more transmitting radiofrequency units. In some embodiments, a single oscillating module mayprovide an oscillating signal to the mixer modules 206, 226, and/or 234,respectively (e.g., optionally via a filter). In one example, theoscillator signal from an oscillator module may be altered (e.g.,oscillation increased or decreased) and provided to a different part ofthe circuit.

Those skilled in the art will appreciate that each of the oscillatormodules 210 and 224 may be the same as each other. For example,oscillator modules 210 and 224 may both be oscillators sharing the sameelectrical properties or, alternately, the oscillator modules 210 and224 may be another kind of oscillator and/or with different electricalproperties.

Each oscillator modules 210 and 224 may include one or more components.For example, the oscillator module 210 may comprise one or moreoscillators.

The signal quality module 230 may be configured to generate a phasecontrol signal to control the phase of a processed signal. In oneexample, the mixer module 232 receives the upconverted RF signal fromthe amplifier/attenuator module 228 and mixes the amplified orattenuated signal with the filtered oscillator signal or the upconvertedsignal from the second upconverter (e.g., mixer module 220, filtermodule 222, and oscillator module 224). The filter module 234 may filterthe signal. A splitter 236 may split the signal to a phase comparatorand a gain comparator. The phase comparator may compare the phase of thesignal from the splitter 236 to a predetermined phase value to generatea phase control signal that may control the phase adjuster 214. The gaincomparator may compare the gain (i.e., amplitude) of the signal from thesplitter 236 to a predetermined gain value to generate a gain controlsignal that may control the AGC module 216

The phase adjuster 214 may comprise a variable phase control circuitconfigured to increase or decrease the phase of the signal to betransmitted. The phase adjuster 214 may comprise any different type ofphase adjuster or phase shifter with different electrical properties. Inone example, the phase adjuster 214 increases or decreases the phase ofthe signal received from the filter module 218. The phase adjuster 214may adjust the phase of the signal based on the phase control signalfrom the signal quality module 230.

The phase adjuster 214 may include one or more components. For example,the phase adjuster 214 may comprise one or more phase control elements.

The AGC module 216 may comprise an automatic gain control (AGC) circuitconfigured to increase or decrease the gain of the signal received fromthe phase adjuster 214. The AGC module 216 may comprise many differenttypes of AGCs with many different electrical properties. In one example,the AGC module 216 increases or decreases the gain of the signalreceived from the phase adjuster 214. The AGC module 216 may adjust thegain of the signal based on the gain control signal.

The AGC module 216 may include one or more components. For example, theAGC module 216 may comprise one or more AGCs.

In some embodiments, the predetermined phase value and amplitude valuemay be the same or substantially similar as the phase and amplitude ofthe wireless signals outputted by one or more other transmitting radiofrequency units. In one example, the phase and the amplitude of one ormore transmitting radio frequency unit may be synchronized.

In some embodiments, the transmitting radio frequency unit 202 maycomprise the waveguide filter 244, the waveguide 246, and/or a diplexer.The waveguide filter 244 may be any filter coupled to the waveguide 246and configured to filter the electromagnetic waves (e.g., remove noise).The waveguide 246 may provide the signal to the antenna via a diplexer.The diplexer may provide the signal to the antenna. The waveguide 246may be any waveguide kind or type of waveguide. For example, thewaveguide 246 may be hollow or dielectric. In some embodiments, thewaveguide 246 comprises a rectangular to circular waveguide.

In some embodiments, the transmitting radio frequency unit 202 and oneor more other transmitting radio frequency units are coherenttransmitters. Reference signal module 248 may provide a reference signalin a coherent transmitting radio frequency unit 202. In someembodiments, the reference signal module 248 receives one or moresignals (e.g., I and Q signals) and passes the signals through a phaselock loop comprising a phase detector 252, filter module 254, andoscillator module 256. The phase detector 228 may detect the phase ofthe incoming signals and/or compare the phase to that of the oscillatorsignal of oscillator module 256. The signal may be filtered by filtermodule 254. The phase may be corrected until the desired phase of thereference signal is reached before providing the reference signal(s) viathe splitter 258.

In various embodiments, the oscillator module 256 shares the oscillatorsignal with one or more other reference signal modules of othertransmitting radio frequency units. The oscillator 256 may also providean oscillator signal to the filter module 208 and/or the filter module222 thereby making oscillator modules 210 and/or 224 unnecessary.

In some embodiments, the amplification/attenuation module 204 receivesthe input signal from a modem and provides an amplified input signal tothe mixer 206. The mixer module 206 may up-convert the amplified inputsignal to a higher intermediate frequency (IF) signal. In oneembodiment, the mixer module 206 may use a filtered signal provided bythe oscillator module 210 and the filter module 208 (e.g., band-passfilter) to up-convert the amplified input signal to the IF signal.

Subsequently, the filter module 212 may filter the IF signal. Thefiltered, IF signal may then be adjusted by the phase adjuster 214and/or the AGC module 216. As noted herein, in some embodiments, thephase and/or amplitude of the filtered, IF signal may be adjusted basedon a radio frequency (RF) detected by the signal quality module 230.

Next, the signal provided by the phase adjuster 214 and the AGC module216 may be amplified or attenuated by the amplification/attenuationmodule 218, before being up-converted to the radio frequency (RF) signalby the mixer module 220. The mixer module 220 may utilize a filteredsignal provided by the oscillator module 224 and the filter module 222.The RF signal may be further filtered by the filter module 226 andamplified or attenuated by the amplification/attenuation module 228before being provided to the optional waveguide filter 244 and optionalwaveguide 246.

As the amplified RF signal is provided to the antenna via the optionalwaveguide filter 244 and waveguide 246, the phase and amplitude of theamplified RF signal may be detected and measured by the signal qualitymodule 230. In some embodiments, the signal quality module 230 may beconfigured to compare the measured phase and amplitude values of the RFsignal against predetermined phase and amplitude values, and to instructvarious components of the transmitting radio frequency unit 202 toadjust the phase or amplitude of the signal to match, approximatelymatch, or meet a condition based on the predetermined values. In someembodiments, the predetermined phase and amplitude values may be setsuch that they match, or meet a condition based on, the phase andamplitude of one or more RF signals outputted by the other transmittingradio frequency units. In doing so, some embodiments may facilitatesynchronization of phase and amplitude between the transmitting radiofrequency units.

The antenna may receive the RF signal from the amplification/attenuationmodule 228 via a diplexer configured to implement passive, frequencydomain multiplexing for RF signals to be transmitted as well as for RFsignals received by the antenna module 138.

An antenna may transmit the RF signal to one or more receiving radiofrequency units. In various embodiments, the antenna may be configuredto transmit the RF signal so that the RF signal spatially combines withRF signals transmitted (i.e., outputted) by other radio frequency units.

In various embodiments, by utilizing the signal quality module 230,phase adjuster 214, and/or AGC module 216, an output phase and amplitudeof the transmitter may be accurately measured, controlled, and set.

It will be appreciated that a “module” may comprise software, hardware,firmware, and/or circuitry. In one example, one or more softwareprograms comprising instructions capable of being executable by aprocessor may perform one or more of the functions of the modulesdescribed herein. In another example, circuitry may perform the same orsimilar functions. Alternative embodiments may comprise more, less, orfunctionally equivalent modules and still be within the scope of presentembodiments. For example, as previously discussed, the functions of thevarious modules may be combined or divided differently.

FIG. 3 is a block diagram of a signal quality module 300 for controllingboth phase and gain of the signal in some embodiments. Differenttransmitting radio frequency units may use different signal qualitymodules. In some embodiments, only the phase is adjusted in the mannerdescribed herein. In various embodiments, both the phase and the gainare adjusted in this manner. In that instance, the transmitting radiofrequency unit may comprise the signal quality module 300 of FIG. 3. Instill other embodiments, the transmitting radio frequency unit may onlyadjust gain in this manner. In that instance, the transmitting radiofrequency unit may include the gain comparator but not the phasecomparator.

The signal quality module 300 may comprise a mixer module 304, a filtermodule 308, a splitter 310, a phase comparator 312, a gain comparator314, an RF adaptive path module 316, an amplifier/attenuator module 320,and an amplifier/attenuator module 324.

The mixer module 304 of the signal quality module 300 may receive anoscillator signal (e.g., from oscillator module 210, 224, or 256) viapath 306 and an RF signal via path 302. The RF signal may be received bya coupler. In various embodiments, by mixing the RF signal with theoscillator signal, the frequency of the signal may be reduced. As such,the phase comparator and/or the gain comparator may be less expensivethan comparators that are required to function with higher frequencysignals.

The filter module 308 filters the mixed signal from the mixer module 304and provides the signal to the splitter 310. The splitter 310 may splitand provide the signal to the phase comparator 312, the gain comparator314, and the RF adaptive path module 316. In some embodiments, thefilter module 308 is optional.

Those skilled in the art will appreciate that a legacy transmittingradio frequency unit may comprise the mixer module 304, filter module308, and RF adaptive path module 316 for providing the necessary signalto an adaptive module (see FIG. 5). As a result, adding the splitter310, the phase comparator 312, and/or the gain comparator 314 topreexisting equipment may allow for the leveraging power from multipletransmitters but with less expense.

The phase comparator 312 may be a chip, a processor, or a moduleconfigured to compare the phase of the signal from the splitter 310 withthe predetermined phase value from the predetermined values module 318.In one example, the phase comparator 312 may be an RF/IF detector. Thephase comparator 312 generates a phase control signal based on thecomparison and the amplifier/attenuator module 320 amplifies orattenuates the phase control signal before providing the phase controlsignal to the phase adjuster.

Like the phase comparator 312, the gain comparator 314 may be a chip, aprocessor, or a module configured to compare the gain of the signal fromthe splitter 310 with the predetermined gain value from thepredetermined values module 318. In one example, the gain comparator 314generates a gain control signal based on the comparison and theamplifier/attenuator module 324 amplifies or attenuates the phasecontrol signal before providing the gain control signal to an AGCmodule. The phase control signal and the gain control signal may beprovided over paths 322 and 326, respectively.

The RF adaptive path module 316 may receive the signal from the splitter310 and provide the adaptive signal to the adaptive module. Thepredetermined values module 318 may be any storage (e.g., computerreadable media) that stores the predetermined phase value and thepredetermined gain value.

The predetermined phase value and/or the predetermined gain value may beset within the predetermined values module in any number of ways. Invarious embodiments, a user may set the predetermined phase value and/orthe predetermined gain value within a chip. In some embodiments, a pilotsignal is sent to one or more transmitting radio frequency units. Thephase comparator 808 may set the predetermined phase value and/or thepredetermined gain value based on the pilot signal.

In various embodiments, one transmitting radio frequency unit mayreceive the predetermined phase value and/or the predetermined gainvalue from another transmitting radio frequency unit. For example, afirst transmitting radio frequency unit may request the predeterminedphase value and/or the predetermined gain value from a digital deviceand/or another transmitting radio frequency unit. The digital device ortransmitting radio frequency unit may provide the predetermined phasevalue and/or the predetermined gain value to the requesting transmittingradio frequency unit. In some embodiments, a transmitting radiofrequency unit provides the predetermined phase value and/or thepredetermined gain value to one or more other predetermined phase value(e.g., when the transmitting radio frequency unit changes, atpredetermined intervals, or upon request by a user).

The gain and/or the phase of a signal may be adjusted at any pointwithin the transmitting radio frequency unit. Further, the gain and/orthe phase of the signal may be adjusted any number of times. In oneexample, the phase of the signal is adjusted multiple times based on thesame phase control signal. In another example, the phase of the signalis compared multiple times to one or more predetermined phase values andadjusted based on the comparison.

Although the signal quality module 300 is described as receiving anoscillator signal and a RF signal via the mixer module 304, thoseskilled in the art will appreciate that the signal quality module 300may receive only one signal or more than one signal. For example, themixer module 304 may be optional and the signal quality module 300 mayfilter and compare the phase and/or gain of a signal from any part ofthe circuit of the transmitting radio frequency control module. In someembodiments, the signal quality module 300 may receive an oscillatorsignal or a filtered oscillator signal from any oscillator, including anoscillator that is part of the reference signal module or from anothertransmitting radio frequency unit. Further, the signal quality module300 may mix the oscillator module with the IF signal, RF signal, or anysignal received by the modem.

FIG. 4 depicts two transmitting radio frequency units 404 and 412 insome embodiments. The system 400 may be configured such that each of thetransmitting radio frequency units 404 and 412 transmit a separatewireless signal such that the signals spatially combine. In someembodiments, radio enclosure 402 comprises the transmitting radiofrequency unit 404. Similarly, the radio enclosure 410 comprisestransmitting radio frequency unit 412. The transmitting radio frequencyunit 404 may provide a signal to the antenna 408 via the diplexer 406for transmission to the receiver 418. Similarly, the transmitting radiofrequency unit 412 may provide a signal to the antenna 416 via thediplexer 414 for transmission to the receiver 418. The signals from bothreceivers may be substantially the same gain and phase. As a result, thesignals may be stronger when both transmitting radio frequency units areactively transmitting.

In one example, a wireless signal spatially combines with one or moreother wireless signals from the other transmitting radio frequency unitsto form a beam carrying the same input signal. Each wireless signal mayhave synchronized phase and amplitude with one or more other wirelesssignals from any number of transmitting radio frequency units. In someembodiments, each wireless signal may have a phase and amplitude that issynchronized with predetermined values (e.g., set by a user, or setaccording to the phase and amplitude output of a designated transmittingradio frequency unit 404 or 412).

In some embodiments, the system 400 implements a protection scheme thatutilizes radio link redundancy. For instance, the system 400 may becapable of 1+1 protection for the radio link between a transmittingcommunications site and a receiving communications site, where both ofthe transmitting radio frequency units are in active mode andtransmitting simultaneously or nearly simultaneously. In one example, ifone transmitting radio frequency unit 402 fails, the other transmittingradio frequency unit 410 may continue to transmit. As a result, eachtransmitting RFU is protected by the other. In some embodiments, theprotection is hitless.

Those of skill in the art will appreciate that the transmitting radiofrequency units 404 and 412 may comprise components that are similar tothose described with respect to the transmitting radio frequency unit202 (see FIG. 2). For example, transmitting radio frequency units 404and 412 may comprise a transmission path that is similar to that of thetransmitting radio frequency unit 202. Further, the transmitting radiofrequency units 404 and 412 may provide similar functionality as thetransmitting radio frequency unit 202.

The antennas 408 and 416 may comprise any kind of antennas. In someembodiments, the antennas 408 and 416 are a part of an array ofantennas, or may be a plurality of antennas that form an array ofantennas. In some embodiments, the antennas 408 and 416 may comprise aphased array antenna or a portion of a phased array antenna. The arrayof antennas may be configured as a planar array of antennas (e.g., 3×4planar array of antennas) or a linear array of antennas (e.g., 1×4linear array of antennas). Each of the antennas 408 and 416 may comprisea similar to dissimilar type of antenna to each other. Further, oneantenna may comprise different electrical properties than the others.Those skilled in the art will appreciate that there may be any number ofantennas and any number of transmitting radio frequency units.

FIG. 5 depicts another transmitting radio frequency unit 502 in someembodiments. The transmitting radio frequency unit 502 may comprise adigital signal processor (DSP) 504, a modem module 506, a predistortionmodule 508, an adaptive module 510, mixer modules 512 and 526, filtermodules 514, 518, 528, and 532, oscillator modules 516 and 530, a phaseadjuster 520, an automatic gain control (AGC) module 522,amplification/attenuation modules 524 and 534, a signal quality module536, waveguide filter 538, and waveguide 540.

The DSP 504 is any processor configured to provide one or more signalsto the modem module 506. The digital signal processor (DSP) module 504may comprise a digital signal processor, or another digital device,configured to receiving a source signal intended for transmission andconverting the source signal to corresponding in-phase (I) andquadrature (Q) signals. For instance, the DSP module 504 may beimplemented using a digital device (e.g., a device with a processor andmemory). Instructions stored on the storage system may instruct the DSPmodule 504 to receive an input signal from a communications networkinterface, convert the input signal to corresponding the in-phase (I)and quadrature (Q) signals, and provide the corresponding in-phase (I)and quadrature (Q) signals.

The modem module 506 may be any modem configured to receive one or moresignals to be transmitted. The modem module 506, in one example, mayreceive an in-phase (I) and quadrature (Q) signals and provide thesignals to the predistortion module 508. The modem module 506 maycomprise a modem device, or another digital device. The modem module 506may be configured to receive in-phase (I) and quadrature (Q) signals andmodulate the in-phase (I) and quadrature (Q) signals to encode theinformation.

The predistortion module 508 may receive the signal from the modemmodule 506 and improve the linearity of the signal. In variousembodiments, the predistortion module 508 inversely models gain andphase characteristics and produces a signal that is more linear andreduces distortion. In one example, “inverse distortion” is introducedto cancel non-linearity. The predistortion module 508 may receive apredistortion control signal from the adaptive module 510. The adaptivemodule 510 may provide the predistortion control signal based on thesample from the signal quality module 536 described herein. Thepredistortion module 508 may provide the I and Q signals to the mixermodule 512.

The mixer module 512, filter module 514, and the oscillator module 516may represent an upconverter configured to upconvert the signals to anintermediate frequency signal. Similarly, the mixer module 526, filtermodule 528, and oscillator module 530 also may represent an upconverterconfigured to further upconvert the signal to an RF signal. Thoseskilled in the art will appreciate that there may be any number ofupconverters configured to upconvert the signals within the transmittingradio frequency unit 502.

The mixer modules 512 and 526 may comprise mixers configured to mix thesignal(s) provided by the modem with one or more other signals. Themixer modules 512 and 526 may comprise many different types of mixerswith many different electrical properties. In one example, the mixer 512mixes I and Q signals received from the filter module predistortionmodule 508 with the filtered oscillating signal from the filter module514 and the oscillator module 516. In another example, the mixer module526 mixes a signal received from the amplifier/attenuator module 524with the filtered oscillating signal from the filter module 528 and theoscillator module 530. One or more of the mixer modules 512 and 526 maybe similar to one or more mixer modules 206, 220, and 232 of FIG. 2.

The filter modules 514, 518, 528, and 532 may comprise filtersconfigured to filter the signal. The filter modules 514, 518, 528, and532 may comprise many different types of filters (e.g., bandpass filter,low pass filter, high pass filter, or the like) with many differentelectrical properties. In one example, the filter module 514 may be aband pass filter configured to filter the oscillation signal (orcomponents of the signal) provided from the oscillator module 516.Similarly, filter modules 514, 518, 528, and 532 may filter signals (orcomponents of the signals) from the oscillator module 516, theoscillator module 530, the mixer module 512, or the mixer module 526,respectively. One or more of the filter modules 514, 518, 528, and 532may be similar to one or more filter modules 208, 212, 222, 226, and 234of FIG. 2.

The oscillator modules 516 and 530 may comprise oscillators configuredto provide an oscillating signal that may be used to upconvert thesignal. The oscillator modules 516 and 530 may comprise any kind ofoscillator with any different electrical properties. In one example, theoscillator module 516 provides an oscillating signal to the filtermodule 514. The oscillator module 530 may provide an oscillating signalto the filter module 528.

The oscillator modules 516 and 530, either individually or together, maybe local or remote. In one example, the oscillating module 516 and/orthe oscillating module 530 may be remotely located and configured toprovide an oscillating signal to one or more transmitting radiofrequency units. In some embodiments, a single oscillating module mayprovide an oscillating signal to both the mixer module 512 and 526,respectively (e.g., optionally via a filter). In one example, theoscillator signal from the oscillator module may be altered (e.g.,oscillation increased or decreased) and provided to a different part ofthe circuit. One or more of the oscillator modules 516 and 530 may besimilar to one or more oscillator modules 210, 224, and 256 of FIG. 2.

The signal quality module 536 may be configured to generate a phasecontrol signal to control the phase of a processed signal. In oneexample, the signal quality module 536 receives the upconverted RFsignal from the amplifier/attenuator module 534 and mixes the amplifiedor attenuated signal with the filtered oscillator signal or theupconverted signal from the second upconverter (e.g., mixer module 526,filter module 528, and oscillator module 530). The signal quality module536 may filter the signal and compare the filtered, mixed signal with apredetermined phase value to generate a phase control signal based onthe comparison.

The phase adjuster 520 may comprise a variable phase control circuitconfigured to increase or decrease the phase of the signal to betransmitted. The phase adjuster 520 may comprise any different type ofphase adjuster or phase shifter with different electrical properties. Inone example, the phase adjuster 520 increases or decreases the phase ofthe signal received from the filter module 518. The phase adjuster 520may adjust the phase of the signal based on the phase control signalfrom the signal quality module 536.

The phase adjuster 520 may include one or more components. For example,the phase adjuster 520 may comprise one or more phase control elements.

The AGC module 522 may comprise an automatic gain control (AGC) circuitconfigured to increase or decrease the gain of the signal received fromthe phase adjuster 520. The AGC module 522 may comprise many differenttypes of AGCs with many different electrical properties. In one example,the AGC module 522 increases or decreases the gain of the signalreceived from the phase adjuster 520. The AGC module 522 may adjust thegain of the signal based on the gain control signal.

The AGC module 522 may include one or more components. For example, theAGC module 522 may comprise one or more AGCs.

In various embodiments, in order to adjust the phase of the signal orthe amplitude of the signal, the signal quality module 536 may providecontrol signals to adjust the in-phase (I) and quadrature (Q) signals toachieve the a desired adjustment. For example, in order to adjust thephase or amplitude of the signal, the signal quality module 536 mayutilize the digital signal DSP 504 to adjust the in-phase (I) andquadrature (Q) signals provided to the modem module 506 to achieve thedesired adjustment based on the predetermined phase value and/or thepredetermined amplitude value. In another example, in some embodiments,the signal quality module 536 may utilize the modem module 506 to adjustthe in-phase (I) and quadrature (Q) signals provided to thepredistortion module 508.

The amplification/attenuation modules 524 and 534 may comprise anamplifier and/or an attenuator configured to amplify and/or attenuate asignal. The amplification/attenuator modules 524 and 534 may be any kindof amplifiers and/or attenuators. Further, the amplification/attenuatormodules 524 and 534 may each comprise amplifiers and/or attenuators withany kind of electrical properties.

In some embodiments, the amplifier/attenuator module 524 receives asignal from the AGC module 522. The amplifier/attenuator module 524 mayamplify or attenuate the signal. Further, the amplifier/attenuatormodule 534 may attenuate the signal (or components of the signal) afterthe signal has been upconverted by the mixer module 526, the filtermodule 528, and the oscillator module 530. The amplifier/attenuatormodule 534 may then provide the signal to the signal quality module 536and/or the waveguide filter 538. One or more of theamplification/attenuation modules 524 and 534 may be similar to one ormore amplification/attenuation modules 204, 218, and 228 of FIG. 2.

Similar to the transmitting radio frequency unit 202, the transmittingradio frequency unit 502 may comprise the waveguide filter 538, thewaveguide 540, and/or a diplexer 542. The waveguide filter 538 may beany filter coupled to the waveguide 540 and configured to filter theelectromagnetic waves (e.g., remove noise). The waveguide 540 mayprovide the signal to the antenna 544 via a diplexer 542. The diplexer542 may provide the signal to the antenna 544. Similar to the waveguide246, the waveguide 540 may be any waveguide kind or type of waveguide.

In various embodiments, by utilizing open loop calibration, the totalphase and amplitude for the whole transmitter path may be calibratedfrom I and Q input to the output of the amplifier/attenuator module 534.In some embodiments, by calibration and look-up tables, the phase andamplitude may be accurately detected, controlled, and set at the Txoutput directly or through adjusting I and Q signals at the input.

FIG. 6 depicts two transmitting radio frequency units 604 and 612 insome embodiments. The transmitting radio frequency units 604 and 612 mayeach receive I and Q signals from a DSP, modulate the signals with amodem, and apply adaptive predistortion. In some embodiments, the system600 applies digital beamforming.

The system 600 may be configured such that each of the transmittingradio frequency units 604 and 612 transmit a separate wireless signalsuch that the signals spatially combine. In some embodiments, radioenclosure 602 comprises the transmitting radio frequency unit 604.Similarly, the radio enclosure 610 comprises transmitting radiofrequency unit 612. The transmitting radio frequency unit 604 mayprovide a signal to the antenna 608 via the diplexer 606 fortransmission to the receiver 618. Similarly, the transmitting radiofrequency unit 612 may provide a signal to the antenna 616 via thediplexer 614 for transmission to the receiver 618. The signals from bothreceivers may be substantially the same gain and phase. As a result, thesignals may be stronger when both transmitting radio frequency units areactively transmitting.

Each wireless signal may have synchronized phase and amplitude with oneor more other wireless signals from any number of transmitting radiofrequency units. In some embodiments, each wireless signal may have aphase and amplitude that is synchronized with predetermined values(e.g., set by a user, or set according to the phase and amplitude outputof a designated transmitting radio frequency unit 604 or 612).

Those of skill in the art will appreciate that the transmitting radiofrequency units 604 and 612 may comprise components that are similar tothose described with respect to the transmitting radio frequency unit202 (see FIG. 2). The antennas 608 and 616 may comprise any kind ofantennas. Further, although only two transmitting radio frequency units604 and 612 are depicted, there may be any number of transmitting radiofrequency units.

FIG. 7 is a flowchart of an exemplary method 700 for transmitting awireless signal in accordance with some embodiments. In step 702, aninput signal intended for transmission may be received by a transmittingradio frequency unit. In some embodiments, the transmitting radiofrequency unit may receive the input signal via a modem and/or a DSP.

In step 704, the transmitting radio frequency unit may generate anindividual wireless signal from the input signal received at step 702.As noted herein, in some embodiments, a plurality of individual wirelesssignals generated by multiple transmitting radio frequency units may beeventually transmitted such that the individual wireless signalsspatially combine to form a beam that carries the input signal (receivedat step 702) from a transmitting communications site to a receivingcommunications site. Depending on the embodiment, each of transmittingradio frequency units may generate their respective signal using thetransmission path similar to the transmitting radio frequency unit 202as illustrated in FIG. 2 and/or transmitting radio frequency unit 502 asillustrated in FIG. 5.

In step 706, the transmitting radio frequency units may set apredetermined phase value and predetermined gain value. Thepredetermined phase value and the predetermined gain value may be set atany time. In some embodiments, the predetermined phase value andpredetermined gain value are set based on the beam intended to be formedby the spatial combination of the individual wireless signals as theyare outputted by the transmitting radio frequency units. Subsequently,if one of the transmitting radio frequency units experiences a failureand/or falls below an acceptable level of performance, in someembodiments, the other transmitting radio frequency units may continueto transmit the signal at the predetermined phase and gain.Additionally, in such a scenario, the predetermined phase value and thepredetermined gain value may be adjusted to account for the beam beingformed by two of the transmitting radio frequency units rather than allthree.

Additionally, in some embodiments, the predetermined phase value andpredetermined gain value may be the same for each transmitting radiofrequency unit and are shared amongst the transmitting radio frequencyunits. In doing so, the transmitting radio frequency units of someembodiments may facilitate synchronization of phase and amplitudebetween the transmitting radio frequency units.

In step 708, each of the transmitting radio frequency units maysynchronize the phase of the individual wireless signal they areoutputting with the phase of the individual wireless signals beingoutputted by the other radio frequency units. As noted herein, in someembodiments, each of the transmitting radio frequency units maysynchronize the phase of their respective individual wireless signal bysharing the predetermined phase value, and/or using the predeterminedphase value to adjust their individual signal's phase. For example, asnoted herein, the predetermined phase value may be set by a user, may bebased on the phase of a wireless signal being outputted by one or moredesignated transmitting radio frequency unit in the system, or may bebased on a calibration process involving one or more transmitting radiofrequency unit in the system.

In step 710, each of the transmitting radio frequency units maysynchronize the amplitude of the individual wireless signal they areoutputting with the amplitude of the individual wireless signals beingoutputted by the other radio frequency units. As noted herein, in someembodiments, each of the transmitting radio frequency units maysynchronize the amplitude of their respective individual wireless signalby sharing the predetermined gain value, and/or using the predeterminedgain value to adjust the individual signal's amplitude. For example, asnoted herein, the predetermined gain value may be set by a user, may bebased on the amplitude of a wireless signal being outputted by one ormore designated transmitting radio frequency unit in the system, or maybe based on a calibration process involving one or more transmittingradio frequency unit in the system.

In step 712, each of the transmitting radio frequency units may transmittheir individual wireless signal to one or more receiving radiofrequency units. In some embodiments, each of the transmitting radiofrequency units may transmit their respective individual wireless signalsuch that the individual wireless signals spatially combine to form abeam that carries the input signal to the one or more receiving radiofrequency units.

It should be understood that those of ordinary skill in the art wouldappreciate that one or more steps of method 700 as illustrated in FIG. 7could be performed in the context of other systems or components.Further, it should be noted that the steps may be performed in anyorder.

Various embodiments are described herein as examples. It will beapparent to those skilled in the art that various modifications may bemade and other embodiments can be used without departing from thebroader scope of the present invention. Therefore, these and othervariations upon the exemplary embodiments are intended to be covered bythe present invention.

What is claimed is:
 1. A system comprising: a first transmitting radiofrequency unit including: a first reference signal module configured toprovide a first reference signal having reference signal propertiesshared with a second reference signal in a second transmitting radiofrequency unit; and a first signal quality module coupled to the firstreference signal module, the first signal quality module configured tosynchronize input signal properties of an input signal with thereference signal properties of the first reference signal to produce afirst synchronized signal; and a first antenna coupled to the firstsignal quality module, the first antenna configured to provide a firstwireless signal corresponding to the first synchronized signal, thefirst wireless signal being spatially combined with a second wirelesssignal from the second transmitting radio frequency unit to form a beamcomprising the first wireless signal and the second wireless signal. 2.The system of claim 1, wherein the reference signal properties of thefirst reference signal comprise one or more of a gain and a phase of thereference signal.
 3. The system of claim 1, wherein the input signalproperties of the input signal comprise one or more of a gain and aphase of the input signal.
 4. The system of claim 1, wherein the firstreference signal module comprises a comparator configured to set thereference signal properties using a pilot signal provided to the firsttransmitting radio frequency unit and to the second transmitting radiofrequency unit.
 5. The system of claim 1, wherein the first referencesignal module comprises a comparator configured to set the referencesignal properties based on a value stored on a chip in the firsttransmitting radio frequency unit.
 6. The system of claim 1, wherein thefirst transmitting radio frequency unit and the second transmittingradio frequency unit are part of a 1+1 transmitter protection system. 7.The system of claim 1, wherein the first transmitting radio frequencyunit and the second transmitting radio frequency unit are part of a 1+Ntransmitter protection system.
 8. The system of claim 1, wherein thesecond transmitting radio frequency unit comprises: a second referencesignal module configured to provide the second reference signal; asecond signal quality module coupled to the second reference signalmodule, the second signal quality module configured to synchronize inputsignal properties of the input signal with the reference signalproperties of the second reference signal to produce a secondsynchronized signal; and a second antenna coupled to the second signalquality module, the second antenna configured to provide the secondwireless signal.
 9. The system of claim 1, wherein the first antenna ispart of an antenna array.
 10. The system of claim 9, wherein the antennaarray comprises a phased antenna array.
 11. The system of claim 9,wherein the antenna array comprises one or more of a linear antennaarray and a planar antenna array.
 12. A method comprising: providing afirst reference signal having reference signal properties shared with asecond reference signal in a second transmitting radio frequency unit;synchronizing input signal properties of an input signal with thereference signal properties of the first reference signal to produce afirst synchronized signal; and providing a first wireless signalcorresponding to the first synchronized signal, the first wirelesssignal being spatially combined with a second wireless signal from thesecond transmitting radio frequency unit to form a beam comprising thefirst wireless signal and the second wireless signal.
 13. The method ofclaim 12, wherein the reference signal properties of the first referencesignal comprise one or more of a gain and a phase of the referencesignal.
 14. The method of claim 12, wherein the input signal propertiesof the input signal comprise one or more of a gain and a phase of theinput signal.
 15. The method of claim 12, further comprising setting thereference signal properties using a pilot signal provided to a firsttransmitting radio frequency unit and to the second transmitting radiofrequency unit.
 16. The method of claim 12, wherein a first transmittingradio frequency unit and the second transmitting radio frequency unitare part of a 1+1 transmitter protection system.
 17. The method of claim12, wherein a first transmitting radio frequency unit and the secondtransmitting radio frequency unit are part of a 1+N transmitterprotection system.
 18. The method of claim 12, further comprising:providing the second reference signal; synchronizing the input signalproperties of the input signal with the reference signal properties ofthe second reference signal to produce a second synchronized signal; andproviding the second wireless signal with an antenna.
 19. The method ofclaim 18, wherein the antenna is part of an antenna array.
 20. A systemcomprising: means for providing a first reference signal havingreference signal properties shared with a second reference signal in asecond transmitting radio frequency unit; means for synchronizing inputsignal properties of an input signal with the reference signalproperties of the first reference signal to produce a first synchronizedsignal; and means for providing a first wireless signal corresponding tothe first synchronized signal, the first wireless signal being spatiallycombined with a second wireless signal from the second transmittingradio frequency unit to form a beam comprising the first wireless signaland the second wireless signal.